Inside the hopeful search for a vaccine to beat a virus that causes cervical tumors

It has an exotic name, but the human papillomavirus is actually a very commonplace sexually transmitted disease. More than half of U.S. women will develop sex-related HPV infections at some point in their life, and in most cases the immune system knocks the virus out before it can do any damage. In some cases, however, the infection becomes chronic, with measurable levels of the virus remaining in the system. Perhaps 5% of these women will eventually develop precancerous lesions that could lead to cervical cancer. Or at least that's what would happen if they did not undergo routine Pap smears, which...